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Why Balcony Solar Panels Haven’t Taken Off in the US (www.wired.com)
submitted 1 year ago by to c/technology@lemmy.world
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[–] 25 points 1 year ago* (2 children)

It detects a voltage connected to the plug and starts feeding with slightly higher voltage, done.

These are really common in Germany, even being sold as sets at supermarkets occasionally.

As long as you have one of the old Ferraris style meters, it just runs backwards, these usually pay for themselves in about three years on a sunny balcony that way.

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  • [–] 5 points 1 year ago (2 children)

    Huh, the wiring just supports power spontaneously coming from an exit point rather than an entry? Is that commonplace?

    Either way, that's fascinating! Thanks for taking the time to enlighten me!

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  • [–] 21 points 1 year ago* (last edited 1 year ago) (1 child)

    Huh, the wiring just supports power spontaneously coming from an exit point rather than an entry? Is that commonplace?

    Why wouldn't it? Electrical wiring isn't a one way road, electricity (this is an extreme oversimplification, especially when it comes to AC) will always flow from points of high voltage to points of lower voltage. That's how solar inverters feed into the grid. Raise their voltage a tad bit higher than the grid and match the frequency and phase of the grid until the outflow matches their maximum available power.

    Is that commonplace?

    That is a hard question, because this isn't a feature, it's how things are. Only thing one needs to take care of is that the solar inverter doesn't deliver so much power that the circuit can consume beyond the circuit breakers capacity, otherwise the breaker would be rendered useless. That's why these small plug inverters are limited to 800W in Germany, that puts the entire possible load on a 16A circuit into the general upper limit that is still within the safety margin fro 16A circuits.

    EDIT: Now before someone gets the bright idea to connect their diesel generator to the grid this way: Don't. It will not be in sync or phase and that will make something spectacular happen, but it will not supply the grid. Either have an expensive generator that is able to sync to the grid or have a grid disconnect and switchover in front of your generator plugin socket.

    EDITEDIT: Also please never connect an island capable solar inverter to a plug. The ones described above are safe that way, because they wait for grid voltage to be available before they do anything, so there will never be high voltage on the open plug. An island capable solar inverter does by definition not do that. There will be high voltage on the plug and it will kill you and it will hurt like a fucker the entire time you're dying.

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  • [–] 1 point 1 year ago (2 children)

    I guess I've pictured electricity a bit too much like water. I still don't quite get how or why this works, but it's really cool that it does!

    That said I've no plans on messing around with that kind of thing as I'm terrified of electricity. I electrocuted myself as a kid and that experience stuck. Rather like I did to the dough hooks I stuffed into an extension cord.

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  • [–] 9 points 1 year ago (1 child)

    On some level, water would work the same way. If you were to collect water from somewhere, feed it into a pump and hook that up to your kitchen faucet, as soon as you increased pressure a little above that of the public water pipe, water would flow backwards from your faucet through the pipes in the house into the public water supply and your water meter might run backwards, depending on its construction.

    disclaimer: Unlike freshly harvested AC electricity from a solar inverter, home collected water does not meet the hygiene standards for public supply. Absolutely do not do that either.

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  • [–] 5 points 1 year ago* (2 children)

    And this is why the UK has separated hot and cold water taps.
    Your hot water used to come from a rainwater tank on the roof, and it was illegal to pipe it to a mixing faucet because if something went wrong with the cold water site it could pull undrinkable hot water from these tanks and faucets and contaminate all the drinking water.

    Works for these plug-in solar panels too - illegal here in Finland, because if the grid went down, these types of panels could keep feeding the house, out to the street, and electrocute a line worker.

    (Also because installing solar panels is a well protected job over here, can't touch that occupation and their revenue stream)

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  • [–] 5 points 1 year ago*

    because if the grid went down, these types of panels could keep feeding the house, out to the street, and electrocute a line worker

    The inverter in these is designed to shut down if it doesn't detect a waveform from the grid to sync with - they are unable to create a 50 Hz AC wave on their own. As long as the hardware is legit (which is a big if with how easy it is to get unsafe junk in from China) there is no safety issue, it's purely regulatory.

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  • [–] 1 point 1 year ago*

    It's not electrons "reaching" a point that does the work, it's the fact that they move. A generator or a battery just applies the force that makes them move (voltage).

    You can in fact picture it like water, just in a circular, perfectly level channel. When you paddle at one point in the channel the water starts to move and can do work at another point. It doesn't really matter where exactly you are paddling.

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  • [–] 4 points 1 year ago

    My parents recently bought a couple and put them on the shed, you plug it in and magically, it feeds electricity into your home power network. No idea how bit it definitely works!

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